The invention relates to a method for detecting an object in a substrate as well as a device for detecting an object in a substrate
Typical objects that are detected in substrates are water pipes, reinforcing bars, electrical lines, power lines, accumulations of moisture and cavities. Within the scope of this patent application the term “object” includes any fixed, liquid and gaseous objects that are embedded in substrates. Because of the risk of injury associated with severing a power line, a detecting device must detect a power line with a high degree of reliability. A power line is a current-carrying electrical line which generates a magnetic field during operation that can be used to detect the power line. Even though telephone and antenna cables constitute electrical lines, they carry only very little current and do not fall under the definition of the term “power line” as used in the scope of this patent application.
German Patent Document No. DE 102 05 002 A1 discloses a method and a device for detecting an object in a substrate. The detecting device includes a sensor unit, a control and evaluation unit and a display unit. The control and evaluation unit is connected to the sensor unit and the display unit via a first and second real-time communication connection. In this case, along with communication connections without a time delay, the term “real-time communication connection” also includes communication connections in which the time delay between acquisition of the receive signals by the sensor unit and display of a depth cross-sectional image on the display unit is so short that the depth cross-sectional image on the display unit is essentially reproducing a depth cross-sectional image through the substrate at the current position of the sensor unit.
The detecting device is guided over the surface of the substrate in parallel, linear measuring tracks. The receive signals acquired by the sensor unit are transmitted by the first real-time communication connection to the control and evaluation unit while other sectional lines are being scanned and the control and evaluation unit calculates a depth cross-sectional image of the substrate. The depth cross-sectional image is transmitted by the control and evaluation unit to the display unit via the second real-time communication connection while other sectional lines are being scanned, and the display unit displays the depth cross-sectional image through the substrate on the display unit. In order to improve clarity and spatial orientation for the operator, the depth cross-sectional image includes, among other things, a depth scale and graphic pattern for displaying the objects.
The disadvantage is that the detecting device has to be guided over the surface of the substrate in several parallel measuring tracks in order to acquire a specific surface of the substrate. The depth cross-sectional images of the individual measuring tracks are displayed on the display unit virtually in real time, but the depth cross-sectional images of the parallel measuring tracks are not displayed at the same time so that the operator does not have any spatial orientation about where the objects are located in the substrate.
In contrast, the object of the present invention consists of further developing a method and a device for detecting an object in a substrate to the effect that the operator obtains spatial orientation of where the objects are located in the substrate. In addition, the operator's effort during detection is reduced.
The method for detecting an object in a substrate is characterized according to the invention by the further steps of simultaneous reception of at least one further receive signal by a further sensor element of the sensor unit and simultaneous calculation of at least one further depth cross-sectional image from the at least one further receive signal by the control and evaluation unit. Because a further receive signal is received at the same time as the receive signal, it is possible for the control and evaluation unit to calculate at least one further depth cross-sectional image. During a feed movement of the detecting device over the substrate, several depth cross-sectional images are calculated and displayed on the display unit so that the operator's effort during detection is reduced.
A plan view is preferably calculated from the depth cross-sectional images and displayed on the display unit, wherein the plan view is calculated as the mean value, median, maximum value or weighted sum over a depth range between a first depth and a second depth. From the plan view, the operator obtains a direct spatial impression of where the objects are located in the substrate. It is especially preferred that the first and second depths are adjustable so that the operator is able to restrict the objects displayed in the plan view to specific depth ranges.
It is especially preferred that only objects that exceed a threshold value are depicted in the plan view, wherein the threshold value is preferably adjustable. The adjustability of the threshold value makes it possible for the operator to adapt the depiction of the plan view to his/her requirements. It is possible to eliminate artifacts and interference via the threshold value so that only the objects that the operator would like to display are displayed in the plan view.
It is especially preferred that the depth cross-sectional images are interpolated. Due to the interpolation of the depth cross-sectional images, it is possible to increase the resolution of the objects in the plan view. The interpolation is suitable for example for guided detecting devices, which are moved over the substrate in a linear feed movement. In a horizontal direction perpendicular to a feed direction, the resolution of the objects is essentially determined by the number of sensor elements, whereas a high level of scanning takes place in the feed direction, which produces a high resolution of the objects. Due to the interpolation of the depth cross-sectional images, it is possible to increase the resolution in the horizontal direction.
In a preferred embodiment, further receive signals are received by sensor elements of a further sensor unit. It is possible to increase the quality and reliability of the measurement by using several sensor units with different sensor properties for receiving receive signals of the objects. The term “sensor property” includes all properties of sensor units such as size, position, orientation, sensor type. Additional sensor properties are included in the case of radar sensors, such as polarization (linear, circular, parallel, perpendicular), bandwidth, frequency band, modulation type, and in the case of inductive sensors, additional properties such as amplitude, frequency range, excitation pattern, sensitivity, band width.
In a preferred method variant, the sensor unit is moved over the substrate in a first feed direction and a second feed direction in parallel measuring tracks, wherein several depth cross-sectional images are calculated from the receive signals in the first and second feed directions. In doing so, it is especially preferred that a common plan view is calculated from the depth cross-sectional images of the first and second feed directions and is displayed on the display unit. Because a common plan view is calculated from the depth cross-sectional images of the individual measuring tracks and displayed on the display unit, it is also possible to detect larger surface areas and display them in a common measurement image.
In a first variant, common depth cross-sectional images are calculated from the receive signals of the sensor unit and the receive signals of the further sensor unit by the control and evaluation unit and a common plan view is calculated from the common depth cross-sectional images. The advantage of common depth cross-sectional images and a common plan view is that all objects are displayed in one depiction. In addition, the reliability when detecting an object type is increased if the object type is detected in different ways.
In a second variant, separate depth cross-sectional images are calculated from the receive signals of the sensor unit and the receive signals of the additional sensor unit by the control and evaluation unit and separate plan views are calculated from the separate depth cross-sectional images. The advantage of separate depth cross-sectional images and a separate plan view is that it is possible to adapt the display and calculation parameters for the depth cross-sectional images and the plan view to the depth range and the objects being detected.
In the case of the device for detecting an object in a substrate, it is provided according to the invention that the sensor unit have at least one further sensor element and the control and evaluation unit be designed to calculate simultaneous depth cross-sectional images from the receive signals of the sensor elements. A sensor unit with several sensor elements makes it possible to simultaneously receive several receive signals and for parallel depth cross-sectional images to be calculated by the control and evaluation unit.
The control and evaluation unit is preferably designed to calculate a plan view from the depth cross-sectional images as the mean value, median, maximum value or weighted sum over a depth range between a first depth and a second depth and display it on the display unit, wherein the first depth and the second depth are especially preferably designed to be adjustable. In addition to the cited mathematical functions of mean value, median, maximum value or weighted sum, any appropriate mathematical function may be used to calculate the plan view. The plan view provides the operator with a direct spatial orientation of the objects to the substrate. Because of the adjustability of the first and second depths, it is possible for objects that are embedded in the substrate at different depths to be displayed separately from one another in the plan view. The operator is able to restrict the object displayed in the plan view to different depth ranges.
A horizontal surface area in which the plan view is displayed is preferably designed to be adjustable, wherein the surface area is separately adjustable in a first and second horizontal direction. The adjustability of the horizontal surface area makes it possible for the operator to restrict the plan view to the surface area that is of interest to him/her. Because the size of the display unit is limited, it is possible to adapt the scale of the plan view to the set horizontal surface area.
In a preferred embodiment, at least one depth cross-sectional image and the plan view are able to be displayed simultaneously on the display unit. In doing so, the depth cross-sectional image displayed on the display unit is especially preferably adjustable via a rocker switch, wherein the position of the rocker switch is displayed in the plan view. The operator is able to use the rocker switch to switch back and forth between the depth cross-sectional images. Because the position of the rocker switch is displayed in the plan view, the operator is aware of the location at which he/she is viewing the depth cross-sectional image.
In a preferred embodiment, a first sensor unit having first sensor elements and a second sensor unit having second sensor elements are provided, wherein the second sensor elements differ in at least one sensor property from the first sensor elements. By using different sensor types or using a sensor type with different sensor properties it is possible to reliably detect different objects or objects at different depths of the substrate. For example, inductive sensors in the form of coils with a small coil diameter reliably detect objects near the surface and close to each other (not much separation), whereas coils with a large coil diameter reliably detect objects that are far away from the surface. By combining small and large coils, objects that are close to the surface and those that are far away from the surface are detected reliably. Depending upon the field of application of the detecting device, all known sensor elements may be combined with one another.
It is especially preferred that the first sensor unit is designed to detect any desired object and the second sensor unit is designed to detect a power line. Because of the risk of injury associated with severing a power line, a detecting device must detect a power line with a high degree of reliability. Because of the second sensor unit, which is provided exclusively to detect power lines, the reliability of detecting a power line is increased. The first sensor unit makes it possible to determine for example the spatial arrangement of the objects in the substrate and the second sensor unit is used to determine which of the objects constitute power lines.
It is especially preferred that the measuring results of the first sensor unit can be displayed on the display unit in a first display mode, the measuring results of the second sensor unit in a second display mode and the measuring results of the first and second sensor units in a third display mode. In the case of detecting devices that have two different sensor units, the control and evaluation unit calculates common depth cross-sectional images and/or separate depth cross-sectional images. A common plan view is calculated from the common depth cross-sectional images and displayed on the display unit. The advantage of common depth cross-sectional images and a common plan view is that all objects are displayed in one depiction. Separate depth cross-sectional images and separate plan views calculated therefrom may be displayed on the display unit simultaneously or in succession.
Exemplary embodiments of the invention will be described in the following on the basis of the drawings. These drawings are not necessarily supposed to represent the exemplary embodiments to scale, rather the drawings are executed in a schematic and/or slightly distorted form when this is useful for explanatory purposes. Reference is made to the pertinent prior art with respect to additions to the teachings directly identifiable from the drawings. It must be borne in mind in this case that a wide range of modifications and changes related to the form and detail of an embodiment may be undertaken without deviating from the general idea of the invention. The features of the invention disclosed in the description, the drawings as well as in the claims may be essential for the further development of the invention both separately as well as in any combination. Moreover, all combinations of at least two features disclosed in the description, the drawings and/or the claims fall within the scope of the invention. The general idea of the invention is not restricted to the exact form or detail of the preferred embodiment described and depicted in the following or restricted to a subject matter which would be limited as compared to the subject matter claimed in the claims. In the case of any dimensioning ranges given, values within the stated limits are also meant to be disclosed as limit values, and be applicable at will and claimable. For the sake of simplicity, the same reference numbers are used in the following for identical or similar parts having an identical or similar function.